Fire ants don't leave in winter — they remodel. In cool months along coastal Alabama and Northwest Florida, colonies build taller, steeper, south-facing mounds that work like solar collectors, pulling in heat on sunny days. On cold mornings the ants crowd the warm sunlit side near the surface, which makes mounds more visible — and makes late winter and early spring a smart, low-risk time to treat before colonies reproduce.
No. The imported fire ant (Solenopsis invicta) is well adapted to our mild, humid winters. Research shows the mound itself acts as a passive solar collector: it warms faster than the surrounding soil and faster than a flat, moundless nest, both in direct sun and even in shade. That heat lets the colony keep developing brood through the cooler months.
When the sun sits lower in the sky, fire ants change the shape of the mound to catch more of it. Field surveys across the Southeast found mounds are tallest, most elongated, and have the steepest south-facing slopes during the low-sun, cooler parts of the year, with peak overall volume arriving in spring. A cold-weather mound is engineered to grab solar heat, so it stands taller and faces the sun.
Because our winters are mild, fire ants stay active far more of the year here than in colder states, and treatment timing is driven by temperature, not the calendar. Two windows matter most: late winter to early spring (treat established mounds before colonies produce reproductives), and warm, sunny days (when ants tend brood near the surface and treatments reach the colony efficiently).
Tall, hard mounds on open, sunny ground this winter signal an active, growing colony — not a dying one. Disturbing the mound only scatters the ants. A targeted treatment timed to a warm spell is far more effective and much safer for kids, pets, and your lawn.
Are fire ants active in winter in Alabama and Florida? Yes. Mild Gulf Coast winters keep colonies active; they build taller, sun-facing mounds and keep developing brood rather than dying off.
Why are fire ant mounds taller in cold weather? The mound works as a solar collector. With the sun lower in the sky, ants build taller, steeper, south-facing mounds to absorb more heat.
Should I treat fire ants in the winter? Late winter and early spring are excellent times to treat, before colonies produce reproductives. Treat on a warm, sunny day while ants are near the surface.
Will knocking down the mound get rid of the colony? No — disturbing a mound usually scatters the ants. A targeted treatment that reaches the queen is what eliminates it.
EnSec Pest & Lawn has been protecting Gulf Coast homes since 1997. Get a free estimate today.
